In connectors used in high speed data transfer systems, such as communications devices that transmit data signals at speeds exceeding 2 Gbps, the impedance of the signal paths inside the connector must be maintained at a uniform value.
An exemplary connector 101 that is used to maintain a uniform impedance is shown in FIGS. 8 and 9. This connector 101 comprises an insulating housing 110 and a plurality of boards 120 that are supported in a row in the housing 110. Each board 120 is constructed from an insulating board material such as FR4, and a pattern comprising a plurality of signal conductors 121 and a plurality of ground conductors 122 is formed such that the ground conductors surround the signal conductors 121 with a specified distance retained between the respective conductors. The pattern of signal and ground conductors is disposed on the front and back surfaces of each board 120. The signal conductors 121 extend from a first side 123 of the board 20 configured to mate with a mating connector (not shown in the figures) to a second side 124 of the board 120 with mounting pads 124 thereon and configured to be connected to another circuit board (not shown in the figures). The ground conductors 122 extend from points located slightly to the inside of the contacts on the first side 123 to the mounting pads on the second side 124. A plurality of contacts 130 are disposed on the mounting pads at the second side 124 of the respective boards 120 to form an electrical connection to the signal conductors 121 and ground conductors 122.
The housing 110 comprises a front housing portion 111 and an accommodating body 114. The front housing portion 111 comprises a vertical wall 111a and a top 11b that extends rearward (to the left in FIG. 8) from an upper end of the vertical wall 111a. A plurality of slits 112 pass through the vertical wall 111a such that the contacts 123 of the respective boards 120 are passed through the slits 112. Grooves 113a and 113b are respectively formed in protruding wall that extends forward from the lower end of the vertical wall 111a and from the upper end of the vertical wall 111a into which the lower ends and upper ends of the respective boards 120 are inserted. Furthermore, the accommodating body 114 comprises a platform portion 114a that extends in the forward-rearward direction, and a rear vertical wall 114b that extends upward from the rear end of the platform portion 114a. A plurality of grooves 115 are formed in the platform part 114a to receive the second side 124 of the respective boards 120 having the mounting pads disposed thereon. A through-hole (not shown in the figures) is formed in each groove 115, through which one of the contacts 130 connected to the signal conductors 121 and ground conductors 122 is passed. Furthermore, a plurality of grooves 116 are formed in the rear vertical wall 114b, into which the contacts on the first side 123 of the respective boards 120 are inserted. Moreover, engaging posts 117 that engage with the top portion 111b of the front housing portion 111 are formed on the upper end surface of the rear vertical wall 114b. 
In the connector 101 shown in FIGS. 8 and 9, the contacts on the signal conductors 121 of the respective boards 120 at the first side 123 thereof are utilized as male type contacts, and are mated and connected with female type contacts (not shown in the figures) disposed on the side of the mating connector. The plurality of contacts 130 disposed on the mounting pads at the second side 124 of the respective boards 120 are connected to the circuit board. As a result, the impedance of the signal paths inside the connector 101 can be maintained at a uniform value, so that data signals can be transmitted at a high speed.
FIG. 10 shows a configuration in which multi-layer boards 301 and 302 are connected to each other by a connector assembly comprising a first connector 101 shown in FIGS. 8 and 9 and a second connector 201 that is mated with this first connector 101.
Specifically, in the first connector 101, the signal conductors 121 formed on the first side 123 (see FIG. 9) of the respective boards 120 are utilized as male type contacts, and are mated and connected with female type contacts 202 disposed in the second connector 201. The male type contacts 202 of the second connector 201 are connected to the multi-layer board 301. Moreover, the plurality of contacts 130 disposed on the second side 124 (see FIG. 9) of the respective boards 120 are connected to the multi-layer board 302. As a result, the impedance of the signal paths inside the connector assembly comprising the first connector 101 and second connector 201 can be maintained at a uniform impedance value, so that data signals can be transmitted at a high speed.
FIG. 11 shows a connector 401 in which a plurality of female contacts 425 are connected to the respective end parts of a plurality of boards 421, 422, 423 and 424, and these female contacts 425 are secured inside a housing 410. A plurality of signal conductors 421a and ground conductors 421b are formed on the surfaces of the respective boards 421, 422, 423 and 424, and the female contacts 425 are soldered to one end of each of the conductor patterns 421a and 421b. Contacts 426 that are connected to a circuit board (PCB) are disposed on the other ends of the respective conductor patterns 421a and 421b. In FIG. 11, shielding patterns 421c are disposed between the conductor patterns 421a and 421b to prevent crosstalk.
However, the following problems have been encountered in the conventional connector assembly shown in FIG. 10 and the connector shown in FIG. 11.
Specifically, in the connector assembly shown in FIG. 10, since the female contacts 202 disposed inside the second connector 201 have a structure in which these contacts make receiving contact or elastic contact with the signal conductors 121 (formed on the respective boards 120) used as male type contacts during mating, these female contacts are susceptible to damage during mating. Consequently, as insertion and extraction of the first connector 101 and second connector 201 are repeated, there is a high probability that damaged female contacts 202 will be generated. Accordingly, it is desirable that it be easy to replace damaged female contacts 202. However, to replace damaged female contacts 202, it is necessary to release the connection of all of the female contacts 202 with the multi-layer board 301, to remove the second connector 201 from the multi-layer board 301, and to remove the female contact 202 in question from the housing of the second connector 201. Accordingly, such replacement is difficult to accomplish.
For the connector shown in FIG. 11, replacing damaged female contacts 425, requires that the connection of the contacts 426 connected to the circuit board be released from the circuit board, that the connector 401 be removed from the circuit board, that the board to which the female contact 425 in question is attached be removed from the housing 410, and that the female contact 425 in question be removed from the board. Again, such replacement is not easily accomplished.